An Improved Gas Electron Diffractometer – The Instrument, Data Collection, Reduction and Structure Refinement Procedures

Berger, Raphael J. F.; Hoffmann, Manfred; Hayes, Stuart A.; Mitzel, Norbert W.

doi:10.1515/znb-2009-11-1204

Cited by 59 publications

(37 citation statements)

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“…These data were reduced to total intensities by using the program PIMAG by Strand et al [35] (version 040827) and further data reduction (yielding molecular intensity curves), the molecular structure refinement, and the electron wavelength determination (from benzene data) were performed by using version 3.0 of the ed@ed program. [36] Further details about the Bielefeld GED apparatus, the data handling, and approaches to the refinement are given in reference [37]. Full information relating to the refinement is provided in the Supporting Information: The data analysis parameters for each data set (R factors, scale factors, data ranges, weighting points, nozzle-to-plate distances, and electron wavelengths), a list of interatomic distances, amplitudes of vibration, u, and distance corrections for the curvilinear perpendicular motion, k h1 , and refined molecular coordinates for 1 and 2 from the r h1 refinement are also provided.…”

Section: Resultsmentioning

confidence: 99%

Chlorobis(pentafluoroethyl)phosphane: Improved Synthesis and Molecular Structure in the Gas Phase

Hayes

Berger

Mitzel

et al. 2011

Chemistry A European J

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(C(2)F(5))(2)PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C(2)F(5))(3)PF(2). (C(2)F(5))(3)PF(2) was reduced in the first step with NaBH(4) in a solvent-free reaction at 120 °C. The product, P(C(2)F(5))(3), was treated with an excess of an aqueous sodium hydroxide solution to afford the corresponding phosphinite salt Na(+)(C(2)F(5))(2)PO(-) selectively under liberation of pentafluoroethane. Subsequent chlorination with PhPCl(4) resulted in the selective formation of (C(2)F(5))(2)PCl, which was isolated by fractional condensation in an overall yield of 66 %. The gas electron diffraction (GED) pattern for (C(2)F(5))(2)PCl was recorded and found to be described by a two-conformer model. A quantum chemical investigation of the potential-energy surface revealed the possible existence of many low-energy conformers, each with a number of low-frequency vibrational modes and therefore large-amplitude motions. The conformer calculated to be most stable was also found to be most abundant by GED and comprised 61(5) % of the total. The molecular structure parameters determined by GED were in good agreement with those calculated at the MP2/TZVPP level of theory; the only significant difference was a discrepancy of about 3° in the C-P-C angle, which, for the lowest-energy conformer, was refined to 98.2(4)° and was calculated to be 94.9°.

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Section: Resultsmentioning

confidence: 99%

Chlorobis(pentafluoroethyl)phosphane: Improved Synthesis and Molecular Structure in the Gas Phase

Hayes

Berger

Mitzel

et al. 2011

Chemistry A European J

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“…The electron diffraction patterns were recorded on the heavily improved Balzers Eldigraph KD‐G2 gas‐phase electron diffractometer36 at the University of Bielefeld. The experimental details (Table 7) are presented elsewhere 36. The electron diffraction patterns were measured on the Fuji BAS‐IP MP 2025 imaging plates, which were scanned using a calibrated Fuji BAS‐1800II scanner.…”

Section: Methodsmentioning

confidence: 99%

Halogenotrinitromethanes: A Combined Study in the Crystalline and Gaseous Phase and Using Quantum Chemical Methods

Klapötke

Krumm

Moll

et al. 2014

Chemistry A European J

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The halogenotrinitromethanes FC(NO2 )3 (1), BrC(NO2 )3 (2), and IC(NO2)3 (3) were synthesized and fully characterized. The molecular structures of 1-3 were determined in the crystalline state by X-ray diffraction, and gas-phase structures of 1 and 2 were determined by electron diffraction. The Hal-C bond lengths in F-, Cl-, and Br-C(NO2 )3 in the crystalline state are similar to those in the gas phase. The obtained experimental data are interpreted in terms of Natural Bond Orbitals (NBO), Atoms in Molecules (AIM), and Interacting Quantum Atoms (IQA) theories. All halogenotrinitromethanes show various intra- and intermolecular non-bonded interactions. Intramolecular N⋅⋅⋅O and Hal⋅⋅⋅O (Hal=F (1), Br (2), I (3)) interactions, both competitors in terms of the orientation of the nitro groups by rotation about the C-N bonds, lead to a propeller-type twisting of these groups favoring the mentioned interactions. The origin of the unusually short Hal-C bonds is discussed in detail. The results of this study are compared to the molecular structure of ClC(NO2 )3 and the respective interactions therein.

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“…102,103 Data were collected at two different nozzle-to-detector distances, namely 250.0 (MD) and 500.0 mm (LD). The electron diffraction patterns were measured on Fuji BAS IP MP 2025 imaging plates, which were scanned using a calibrated Fuji BAS 1800II scanner.…”

Section: Comparison With Ged Datamentioning

confidence: 99%

Application of classical simulations for the computation of vibrational properties of free molecules

Tikhonov

Sharapa

Schwabedissen

et al. 2016

Phys. Chem. Chem. Phys.

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In this study, we investigate the ability of classical molecular dynamics (MD) and Monte-Carlo (MC) simulations for modeling the intramolecular vibrational motion. These simulations were used to compute thermally-averaged geometrical structures and infrared vibrational intensities for a benchmark set previously studied by gas electron diffraction (GED): CS 2 , benzene, chloromethylthiocyanate, pyrazinamide and 9,12-I 2 -1,2-closo-C 2 B 10 H 10 . The MD sampling of NVT ensembles was performed using chains of Nose-Hoover thermostats (NH) as well as the generalized Langevin equation thermostat (GLE). The performance of the theoretical models based on the classical MD and MC simulations was compared with the experimental data and also with the alternative computational techniques: a conventional approach based on the Taylor expansion of potential energy surface, path-integral MD and MD with quantum-thermal bath (QTB) based on the generalized Langevin equation (GLE). A straightforward application of the classical simulations resulted, as expected, in poor accuracy of the calculated observables due to the complete neglect of quantum effects. However, the introduction of a posteriori quantum corrections significantly improved the situation. The application of these corrections for MD simulations of the systems with large-amplitude motions was demonstrated for chloromethylthiocyanate. The comparison of the theoretical vibrational spectra has revealed that the GLE thermostat used in this work is not applicable for this purpose. On the other hand, the NH chains yielded reasonably good results.

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An Improved Gas Electron Diffractometer – The Instrument, Data Collection, Reduction and Structure Refinement Procedures

Cited by 59 publications

References 1 publication

Chlorobis(pentafluoroethyl)phosphane: Improved Synthesis and Molecular Structure in the Gas Phase

Chlorobis(pentafluoroethyl)phosphane: Improved Synthesis and Molecular Structure in the Gas Phase

Halogenotrinitromethanes: A Combined Study in the Crystalline and Gaseous Phase and Using Quantum Chemical Methods

Application of classical simulations for the computation of vibrational properties of free molecules

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